When Chevrolet announced that its new top of the line Camaro ZL1 would be powered by a 580 hp supercharged V8, putting it at the top of the American muscle car heap, it was a shot across the bow of the Ford Mustang.

The Mustang Shelby GT500 is the current powerhouse of pony cars, its 5.4-liter supercharged V8 pumping out a now less impressive 550 hp. Rumors have been floating around that an even more potent version was in the works for 2013, but details have been scarce. Until now.

MustangsDaily, a blog dedicated to the car, was the first to spot an interesting little tidbit in the recently negotiated labor agreement between Ford and the UAW. In a section outlining planned investments and changes at the company’s facilities, the listing for the Romeo Engine Plant includes a line that reads “The 5.4L Supercharged engine gets upgraded to a 5.8L.”

No grand pronouncement, just an innocuous statement of fact. But, since the GT500 is the only vehicle Ford makes that uses the engine, the implications are clear.

It’s still hard to say what kind of output can be expected from the new motor, but getting more than 580 hp from it should be easy. Word is it could go as high as 620 hp. No hints yet if Ford is working on an active suspension to match the one coming on the ZL1, but another high-tech development should make it easy to see how much quicker the new ‘Stang is.

StangTV has posted images of a 4.2-inch LCD reportedly coming to the 2013 Mustang equipped with a “track app” that can clock the car’s acceleration through the quarter-mile. It even has a drag strip-style “Christmas tree” countdown clock.

The race is on.

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